Chromium dioxide (CrO.sub.2) is well known for its use as a recording medium in high grade magnetic recording tapes. It is used in particulate form. This particulate form of the material prevents its application to high density (gigabit) storage. It has not been possible previously to make acceptable smooth, continuous thin films of CrO.sub.2. This results from the metastable nature of CrO.sub.2 at room temperature. The only previously known method of depositing thin films of CrO.sub.2 has been by chemical transport methods ("Epitaxial Growth of CrO.sub.2 on sapphire in air", Japan J. Appl. Phys., Vol. 17, (1978), 249.). This transport method used flowing O.sub.2 at atmospheric pressure and high temperatures. The substrates are also heated. Due to the process control for the required film thickness, morphology, e.g., roughness, this method leads to additional processing requirements in order to obtain acceptable disc recording material. Attempts to deposit CrO.sub.2 by conventional reactive vapor deposition, diode sputtering, magnetron sputtering, and ion beam sputtering have been unsuccessful. Particulate CrO.sub.2 is usually made using equilibrium processing at high pressures and elevated temperatures. The particulate CrO.sub.2 method is not compatible with the highest densities possible with disk recording.
Theoretical calculations have indicated that CrO.sub.2 is also a useful recording material for magneto-optical recording ("CrO.sub.2 predicted as a half-metallic ferromagnet", K. Schwarz, J. Phys. F. Met. Phys. Vol. 16 (1986) Op. 211-215.). The Faraday rotation is -5.2.times.10.sup.4 deg/cm for light of 2.5 eV photon energy.
Rapid thermal annealing is a known method step in semiconductor device processing which has been in use over the past few years. This method has been used in silicon device technology to:
(a) activate ion implanted impurities, PA1 (b) grow thin films of SiO.sub.2 on silicon, PA1 (c) generally to crystallize disordered or amorphous layers.
In this method, the sample is brought up to a very high temperature (700.degree.-1000.degree. C.) in very short time (order of few milliseconds and shorter). Commercial equipment is available to do this flash annealing process.
When CrO.sub.x (1.6&lt;x&lt;3) coated samples produced by conventional reactive vapor deposition processes are post-heat treated under equilibrium or near equilibrium conditions in oxygen, for example, the film converts from an amorphous mixture to a crystalline Cr.sub.2 O.sub.3 phase. Also, when these vapor deposited films are subjected to rapid thermal annealing, a non-equilibrium heat treatment technique, the same crystalline Cr.sub.2 O.sub.3 phase is produced. This is because Cr.sub.2 O.sub.3 is the thermodynamically stable oxide state in the Cr-O system.